In certain regions of the world, a subsurface hardpan stratum lies below an upper stratum of soil in which plants are planted. This hardpan stratum is generally recognized as being severely deleterious to the growing potential of plants. In particular, the hardpan can form a barrier to the growth of a plant's root system beyond the topsoil stratum.
It is known to break up the hardpan stratum by using a pointed tine which is dragged or otherwise pulled therethrough. Applicant's previously issued U.S. Pat. Nos. 4,815,545 and 4,974,681 are directed to an apparatus and method, respectively, for fracturing the hardpan stratum, and are incorporated herein by reference.
FIGS. 1 and 2 generally illustrate the apparatus disclosed in Applicant's above-identified patents.
A frame 1 is coupled to a main frame 2, which is, in turn, supported by ground engaging wheels 3. The relative height of the wheels 3 is controlled by a hydraulic ram 4 operating through pivotally supported frame 5 on which wheels 3 are mounted.
The main frame 2 supports a blade plow 6 and a cutting coulter disk 9. A tine 8 is provided behind the blade plow 6. The tine 8 is rotatable about a vertical pivot axis at 7, best seen in FIG. 2.
While the above-described apparatus is generally effective for breaking up the hardpan stratum, it has been discovered that it is difficult to achieve consistent results with respect to the depth of hardpan fracture and the straightness of the fracture line. Further, breaking up the hardpan stratum is sometimes, but not always, sufficient to establish a desirable planting and growing zone. Also, the width of the fracture zone created by the apparatus is limited, thereby necessitating multiple passes to achieve a desired width of hardpan fracture.
In addition to the fact that the hardpan stratum has a deleterious effect on plant growth, it is also known that there is an uppermost stratum in soil (i.e., "topsoil") which typically contains the highest concentration of plant nutrients and is generally the most ideal soil medium for plant growth.